System characteristics
27
Planning Aastra 400 DECT systems as of R1.0
syd-0457/1.0 – R1.0 – 10.2012
4. 3 Using external antennas
The SB-8ANT radio unit with 2 external antenna connections is ideally suited for
use in difficult topographical conditions and for special coverage range require-
ments. External antennas are useful
• for rectifying radio signals, thereby achieving a greater range in one particular
direction (e.g. to provide coverage to remote ancillary buildings).
• for providing coverage to an outside area without the shell of the building ob-
structing the propagation of the radio signals (this is achieved by mounting the
radio unit within the building and the antennas outside it).
There are different types of antennas, each with highly specific radio characteristics
for meeting individual coverage requirements; they are best illustrated by radiation
patterns.
The first example shows an antenna that radiates evenly horizontally but has a very
restricted range vertically. This type is known as an omni-directional gain antenna
and improves the horizontal range for a constant radiation output; it is suitable for
open, level premises.
Fig. 10 Example 1: Omni-directional gain antenna
The second example of an antenna, which radiates directionally both horizontally
and vertically, is called a corner reflector antenna or planar antenna. It is ideally
suited for covering distant remote buildings or areas.
Horizontal Vertical
Radiation pattern in relative eld strength
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